Volute type air-heating furnace and blower



Nov. 16, 1948.

F. HIGLEY VOLUTE TYPE AIR HEATING FURNACE AND BLOWER Filed March 20, 1943 3 Sheets-Sheet l F/G- I if RL 0 mm w m m ma Nov. 16, 1948. F. k. H IGLEY I 2,453,912

I VOLUTE TYPE AIR HEATING FURNACE AND BLOWER I iled March 20, 1943 3 Sheets-Sheet 2 Willa INVEN TOR.

A 7' TORNE Y5 lull "Nov. 16, 1948. F. R. HIGLEY 2,453,912 7 I VOLUTE TYPE AIR HEATING FURNACE AND BLOWER Filed March 20, 1943 3 Sheets-Sheet 3 70 INVENTOR.

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A rrae/vz 15 Patented Nov. 16, 1948 VOLUTE TYPE AIR-HEATING FURNACE AND BLOWER Frank R. Higley, Cleveland Heights, Ohio, assignor to Bryant Heater Company, a corporation of Ohio Application March 20, 1943, Serial No. 479,892

Claims. 1

This invention relates to improvements in volute type furnaces, more particularly furnaces in which a segment of the scroll of the centrifugal blower is heated.

One of the objects of the invention is the provision of a furnace of the character stated embodying a minimum of cast material and a relatively large proportion of sheet material.

Another object is the utilization of all surfaces of the combustion chamber as heat exchange surfaces.

A further object is the provision of a furnace of this type with a minimum vertical dimension.

Another object is the provision of a furnace of the volute type in which the scroll and the gas burner are so related that the flame and products of combustion naturally follow the contour of the scroll.

Another object is the provision of a scroll the spiral rate of which is designed to compensate for the increased volume of the air when heated.

Still another object is the disposition of tubular heat transfer elements in such manner and the location of a readily removable draft diverter in such relation thereto that the tubular elements are made accessible for cleaning when the diverter is removed.

Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which:

Fig. 1 is an elevational View of a furnace embodying the invention, one wall of the furnace casing being removed and certain of the parts being broken away or shown in section in order to better illustrate the invention;

Fig. 2 is an elevational view at right angles to that of Fig. 1, the view being taken substantially on the line 2-2 of Fig. 1;

Figs. 3 to 8 inclusive are detail sectional views taken along lines marked 3-3, ll, 5-5, 6, 'l--7, and 8-8 of Fig. 1;

Fig. 9 is a diagram illustrating primarily the rate of generation of the spiral of the blower volute;

Fig. 10 is a diagrammatic showing, partly in vertical section, of a modified form of the invention; and

Fig. 11 is an elevational View of the same on a smaller scale with the outer casing removed.

The present invention has to do with forced air furnaces of the type in which a section of the scroll of a centrifugal blower is a heat exchanger. One of the. important features of the invention is an arrangement in accordance with which a heat exchanger lies outside the blower air stream at the upstream end of the heat exchanger, and gradually extends into the air stream until at its downstream end the heat exchanger lies entirely within the air-stream. By virtue of this arrangement a relatively large heat exchanger surface is provided, and the conductor for the hot gases is gradually brought into a position such that connection may be made with a tubular heat transfer element or elements extending across the path of the air in the air conduit. The arrangement also provides a combustion chamber with a heated lower wall spaced above the bottom of the furnace and affording a preliminary air heating surface. The combustion chamber and the hot gas conductor forming a heat exchanger extends along the blower volute, whereby the radial dimension of this part of the furnace is reduced to a minimum. It is preferably positioned beneath the blower and upwardly along one side thereof, whereby a generally horizontal burner flame introduced into the combustion chamber at one end thereof naturally follows the contour of the scroll.

Another feature of the invention is the provision of a combustion chamber andhot gas conductor wherein the hot gas flow is broken up into a plurality of streams which are caused to flow into separate tubular heat transfer elements that extend into and through the air delivery conduit preferably in a diagonal direction, whereby a long heat transfer surface is wiped by the air as it crosses the said elements.

In the embodiment illustrated in Figs. 1 to 9 inclusive, I have shown a sheet metal casing l0 made up of suitable rectangular members. At the bottom of the casing there is a partition wall 5 i which forms part of the supporting means for a casting I2 that constitutes a combustion chamher and hot gas conductor. The wall H occupies a neutral zone so far as air flow is concerned.

An integral flange E3 on the bottom of the casting is fastened by suitable means to the partition wall i i. The upstream end of this casting is open and is provided with a surrounding flange M to which is secured a transverse partition l5 having an upper inclined wall IS. The walls l5 and I5 extend entirely across the casing and are attached to opposite walls of the latter and the outer edge of the inclined wall I6 contacts a third wall of the casing. In the wall l5 there is an opening I! registering with the open end of the casting, the opening l1 accommodating a fluid burner indicated diagrammatically at Is, this burner being disposed to project a flame IS in a generally horizontal direction, and being preferably a long flame burner. The walls II and together support the casting l2 upon which the rest of the apparatus within the casing is largely carried.

Upon each side of the casting l2 there is an integral pad or land which takes a spiral direction. To these lands the lower edges of blower side plates 2i are secured. These plates have the usual openings 22 for the entrance of air endwise into the blower. The periphery of the blower wheel is indicated at 23. Its shaft 24 is mounted in inverted bearings 25 carried upon angle bars 26 which are secured to the plates M on opposite sides of the openings 22. By virtue of this bearing arrangement no obstacle is presented to the flow of air diagonally upward into the openings 22.

Air from the blower is delivered into an air outlet conduit 21 which projects through the top of the casing, as illustrated. That portion of the blower scroll whichis upstream from the casting I2 is a sheet metal section 28 that is secured to the side plates 2|. has a flange 29 that is fastened to one wall of conduit 21, and has a flange 30 that is mounted between and secured to the flange I4 and the partition l5. A pulley 3| on shaft 24 is driven by a belt 32 from an electric motor 33 which is mounted on a shelf 34 that is hinged at 35 to the adjacent wall of conduit 21. Shelf 34 may be swung into different positions of adjustment and supported there by an adjustable brace 36. 31 represents electric control means for motor 33 comprising a thermostat 38 which extends into the air conduit.

A scroll cut-ofiz" element 39 is mounted within the conduit. The side plates 2| of the blower are in effect continuations of opposed walls of conduit 21, or they can be made integral with those walls if desired. That wall of the conduit which is remote from the blower axis is secured to a transverse pad or land 40 of casting I2.

The casting I2 has an outer wall which curves inward radially on either side to join the lands 20, as indicated by the sectional views, Figs. 3 to 5, inclusive. The outer wall and the spiral of the lands 20 gradually approach each other in the down-stream direction until they come together, as shown in Fig. 6.

The inner wall of the casting which forms a section of the blower scroll. is straight in a transverse direction at the open end of the casting, but from that point onward to a point slightly upstream from the plane of Fig. 6 the inner wall of thecasting is corrugated, the corrugations increasing in depth continuously. The number of these corrugations may vary from a single one to any desired number, three being illustrated. The high and low points 4| and 42 of these corrugations are disposed on opposite sides of the mean volute of the blower. At the plane of Fig. 6 the low points of the corrugations meet and merge with the outer wall of the casting to form a plurality of separate passages 43. From that point on the casting consists merely of separate connectors 44 which may change their cross-sectional shape gradually until in the plane of Fig. 7 they have tear drop, stream-line form.

These connectors 44 receive the lower ends of sheet metal tubular heat transfer elements 45, each of which comprises two stampings having edge flanges welded together and a baffle 46 welded between the flanges at the thick edge of the flue. These battles are employed in order to prevent channeling of the gases flowing through the heat transfer elements. These elements extend diagonally upward at a steep angle, and their upper ends are joined to castings 41 which are bolted to a wall of the conduit 21, there being passages 48 through the castings which register with a suitably formed opening 48 cut in the conduit wall. An apron 49 bolted to the castings and the conduit wall covers the lower portion of this opening 48, so that gases discharged from the tubular elements must flow through an effectively long narrow opening above the apron. Aprons of different widths may be employed to thereby adjust the flue restriction as conditions may require.

On the outer wall of the conduit above the passages ,48 there is a bracket 50 having an upwardly extending lip offset from the surface of the conduit. A draft diverter 5| is removably hung on this bracket by means of a flange 52 which fits behind the oifset lip of the bracket. This diverter 5| is substantially symmetrical about a plane indicated by the line S in Fig. 1. The diverter is principally open on the bottom and one side. It has a second lip 53 substantially identical with lip 52, and by means of these two lips it may be hung upon the bracket 50 in either of two positions. opening surrounded by a flange 54 which is adapted for connection with a flue pipe leading to a chimney. When the draft diverter is mounted as shown in the drawings, the flange 54 extends to the left in Fig. 2. When however the diverter is turned end for end and hangs by means of the lip 53, the flange 54 extends toward the right. Hence by this simple adjustment the diverter may be accommodated to installations in different positions relative to a chimney outlet. This diverter furthermore functions as a manifold, since it collects the gases from a series of tubular elements 45 or the like.

When it becomes desirable to clean out the tubular elements 45, the draft diverter may be lifted 011 and the apron 49 removed, after which a brush may be inserted through the passages 48 into the tubular elements. The cleaning of the casting 12 may be effected by the insertion of a brush through the open end I! of the casting.

In Fig. 9 certain curves are plotted to indicate diagrammatically the approximate relation of the structural parts of the blower and hot gas conductor, as well as the air travel up to the point where it enters the tubular heat transfer elements. Beginning with the zero point of the blower scroll corresponding with the end of the cut-off 39, the points'plotted are at regular 30 intervals, some of which are marked also in Fig. 1. The line 24' represents the axis of the blower wheel. The line 28 represents the volute formed by the surface of the scroll section 28, which extends for 180 from the 'zero point. At 180 the volute divides, one line 4| representing the high points 4! of the corrugations of casting l2 and the other line 42' representing the low points 42 of the corrugations. A mean volute between the lines 4| and 42' is indicated by the broken line 55. 55 represents the outer wall of casting 52, which joins the line 42' at 300. The variation in cross-sectional area of the combustion chamber and hot gas conductor is indicated by the line 51. It will be noted that the rate of generation of the volute remains constant throughout the line 28', or from 0 to 180. From that point on the mean volute 55 follows a steeper curve ac In one end wall there is an complished by suitably increasing the rate of recession of the spiral mean, from the spiral center. This is for the purpose of compensating for thermal expansion of the air by reason of its contact with the hot inner surface of the casting I2.

Air to support combustion may enter the compartment 58 through an opening in the front of the casing, and the air tobe heated may enter the furnace to the rear of the partition wall through the bottom of the housing, as indicated in Fig. 1, or through openings (not shown) provided in the rear wall. The air flows upward over the outer wall of casting 82, which constitutes the first heating stage. It then flows into the end openings 22 of the blower housing and is propelled by the blower wheel against the corrugated inner wall of the cast part of the scroll, which provides a second heating stage. Some of the air leaving the wheel, as indicated by the arrows 60 in Fig. l, flows over the tubular heat transfer elements 25 in a diagonal direction. In other words, its contact with tubular element is along a relatively extended path. This constitutes a third heating stage.

It will therefore be apparent that I have devised a furnace in which the combustion chamber occupies a minimum space and is entirely sur rounded by Walls that constitute heat exchange members, that the combustion chamber and hot gas conductor is arranged at its upstream end outside the path of air propelled by the blower and gradually enters that path until at its downstream end it is enclosed completely therein, that it merges then with one or more tubular heat transfer elements which extend diagonally through the air conduit which is connected with the discharge from the blower, the air being therefore forced to flow over these tubular elements in a diagonal direction and providing relatively long surfaces of contact. It will be observed also that the furnace is one of unusually compact design with the controls readily accessible by the removal of wall panels at one side only of the casing, and that the cleaning of the combustion chamber and the heat transfer elements may be effected with a minimum of effort. In Figs. 10 and 11 I have illustrated a modified form of furnace in which the construction of the combustion chamber and hot gas conductor is considerably simplified in order to adapt it to sheet metal construction. In this form of the invention the advantages of the more complex form previously described are approximated at a lower cost. A blower wheel 55 is mounted in a volute housing comprising a sheet metal scroll 66 which may have a constant rate of spiral through approximately 180, corresponding to the line 28' of Fig. 9. That portion 536' of the scroll which is to be heated may have a rate of spiral somewhat higher, preferably corresponding to the mean volute line 55 of Fig. 9. These two portions of the scroll are welded together at 67, and are formed of sheet metal of a width slightly greater than the blower wheel 65.

Suitable side plates are provided for the combustion chamber 69, the blower and an air conduit it which receives the air discharged from the blower, the plates on each side being substantially coplanar, as indicated in Fig. 11. The bottom wall of the combustion chamber and hot gas conductor is constituted by a sheet of metal ll positioned between and attached to the side walls of the chamber. The sheet H is curved upwardly to meet the downstream end of, scroll section 65' to which it is welded. The rear wall '52 of conduit 18 is welded to the upper endof sheet H, and the connection otherwise between the air conduit and the blower housing, including the scroll, is quite rigid. A burner similar to burner l8 of the first described form of the invention may be employed to direct flame in a generally horizontal direction into the combustion chamber.

The downstream end of the scroll section 66' is curved obliquely'upward, as shown in Fig. 10, and in this end of the scroll adjacent the rear wall E2 of the air conduit there are one or more apertures 13 which are formed to receive a like number of tubular elements 14, the latter being secured to the scroll around the apertures by means of continuous welds.

Each of the tubular elements T4 is here shown as formed of a single stamping of sheet metal rolled into elliptical cross-section, the longitudinal edges 15 being flanged and welded together. Its upper end is welded to the front Wall of air conduit l8 around an aperture 11 therein. The tubular element or elements 14 therefore constitute reenforcing members for the air conduit, as well as constituting conductors for hot gases. The tubular element or elements 14 and the air conduit 70 therefore mutually reenforce each other, and with the scroll 66, 96 in effect constitute a truss. On one of the upstanding members of this truss I support a draft diverter iii, the other member of the truss assisting in the support of the diverter and of the draft pipe which is connected with the diverter. The rigidity imparted to the air conduit by the reenforcing tubuar elements M le of importance also in withstanding shocks encountered in transportation, and enables the furnace to be shipped in fully assembled condition.

The tubular elements 14 extend preferably from the rear of the hot gas conductor 69 upwardly in an inclined direction toward the front of the furnace; with the result that air discharged from the blower wheel and flowing along the surface of the scroll passes over the sides of the tubular elements in a diagonal direction and in a relatively long path. As indicated. by the arrows in Fig. 10, the air discharged from the wheel on its upgoing side also passes over the tubular elements in. a diagonal direction.

In the foregoing description I have necessarily gone somewhat into detail in order to explain fully the particular embodiments of the invention herein illustrated, but I desire it to be understood that such detailed'disclosures are not to be construed as amounting to limitations, except as they may be included in the appended claims.

Having thus described my invention, I claim:

1. In a furnace of the class described, complementary conductor means for heating fluid and blower means for fluid to be heated, having a common heat exchanger wall portion, said blower means including an impeller wheel and a casing therefor having a volute wall extending between side walls to confine and direct discharge from said wheel into a stream having a path of flow leading partially about said wheel, said volute wall includin said common wall portion and said portion having corrugations, said corrugations commencing at the end of said common wall portion upstream of said fluid to be heated and extending from said end in the direction of said stream with gradually increasing depth, said conductor means having another wall portion cooperative with said common wall portion to provide passageway for said heating fluid, said other wall portion having connection with the downstream end of said common wall portion at the bases of said corrugations thereof, whereby said heating fluid passageway, along said common wall portion, has gradual change from a single opening at one end to a plurality of openings at its other end.

2. In a furnace of the class described, complementary conductor means for heating fluid and blower means for fluid to be heated, having a common heat exchanger wall portion, said blower means including an impeller wheel and a casing therefor having a volute wall extending between side walls to confine and direct discharge from said wheel into a stream having a path of flow leading partially about and thence away from said wheel, said volute wall including said common wall portion and said portion having corrugations, said corrugations commencing at the end of said common wall portion upstream of said fluid to be heated and extending from said end in the direction of said stream with gradually increasing depth, said conductor means having another wall portion cooperative with said cormnon wall portion, to provide passageway for said heating fluid, said other wall portion having connection with the downstream end of said common wall portion, at the bases of said corrugations thereof, whereby said heating fluid passageway, along said common wall portion, has gradual change from a single inlet at one end to a plurality of outlets at its other end, and tubular heat transfer elements connected to said outlets and disposed to lead heating fluid therefrom obliquely across said path of flow of the fluid to be heated.

3. In a furnace of the class described, complementary conductor means for combustion products and blower means for fluid to be heated, having a common heat exchanger Wall portion, said blower means including an impeller wheel and a casing therefor having a volute wall extending between side walls to confine and direct discharge from said wheel into a stream having a path of flow leading partially about and thence upwardly away from said wheel, said volute wall including said common wall portion and said portion constituting approximately that quadrant of said volute wall which changes said stream upwardly from horizontal, said volute wall having corrugations, said corrugations commencing at the end of said common wall portion upstream of said fluid to be heated and extending from said end to the other end with gradually increasing depth, said conductor means having another wall portion cooperative with said common wall portion, to provide a combustion chamber and passageway for said combustion products, said other wall portion having connection with the downstream end of said common wall portion, at the bases of said corrugations thereof, whereby said passageway, along said common wall portion, has gradual change from a single opening for horizontal inlet at one end to a plurality of upwardly directed outlet openings at its other end, burner means disposed adjacent said inlet opening to direct its products of combustion along said passageway, and means connected with said outlet openings for removal of said combustion products.

4. In a furnace of the class described, blower means for fluid to be heated, having .a heat exchanger wall portion, said blower means including an impeller wheel and a casin therefor having a volute wall extending between parallel side walls to confine and direct discharge from said wheel into a stream having a path of flow leading partially about and thence away from said wheel, means for heating a segmental portion of said volute wall, said heated wall portion having a greater rate of spiral recession than the remainder of said volute wall, to compensate for thermal expansion of said stream within the corresponding portion of said casing.

5. In a furnace of the class described, blower means for fluid to be heated, having a heat exchanger wall portion, said blower means including an impeller wheel and a casing therefor having a volute wall extending between parallel side walls to confine and direct discharge from said wheel into a stream having a path of flow leading partially about and thence away from said wheel, means for heating a downstream end portion of said volute wall, said end portion having a greater rate of spiral recession than the volute wall portion upstream thereof.

FRANK R. HIGLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 19,102 Dibble Mar. 6, 1934 1,648,192 Prell Nov. 8, 1927 1,877,905 LeGrand Sept. 20, 1932 2,013,237 Funk Sept. 3, 1935 2,037,998 Norquist Apr. 21, 1936 2,053,036 Jones Sept. 1, 1936 2,119,140 Payne May 31, 1938 2,180,212 Morrow Nov. 14, 1939 2,190,349 Beam Feb. 13, 1940 2,221,647 Mooney Nov. 12, 1940 2,245,586 Holmann June 17, 1941 2,258,790 Murphy Oct. 14, 1941 2,313,933 Goerg Mar. 16, 1943 2,330,122 Higley Sept. 21, 1943 FOREIGN PATENTS Number Country Date 528,398 Germany June 29, 1931 

